Russian police have detained three suspects, including a star dancer, over January's acid attack on the Bolshoi ballet artistic director.

Sergei Filin, 42, was struck with sulphuric acid by a masked assailant as he was entering his apartment building through a dark parking lot in January.

He spent about two weeks in a Moscow hospital getting treatment for burns to his face and having a series of surgeries on his eyes.

He has since been moved to Germany for further treatment that may take months. His sight was last reported to have been partially recovered in one eye.

Among the three was dancer Pavel Dmitrichenko, who sources said was suspected to be the mastermind of the attack.

The other two men were 35-year-old Yury Zarutsky, an ex-convict, who was named as the man suspected of throwing acid in Filin's face, and Andrei Lipatov, a driver who took the suspected attacker to the scene of the crime.

Dmitrichenko joined the theatre in 2002. He recently danced the title role in Sergei Prokofiev's "Ivan the Terrible" and had been due to appear next in Sleeping Beauty on March 16.

Russian media speculated that Dmitrichenko could have had a motive because his girlfriend, a young ballerina at the theatre Anzhelina Vorontsova, had been involved in conflicts with Filin over the allocation of roles.

"Dmitrichenko actively spoke out to defend the young soloist," wrote Izvestia daily, citing a source in the theatre who described Dmitrichenko as having a "stormy temperament".

Filin had recently refused Vorontsova a solo role in "Swan Lake", reported Gazeta.ru news site, citing a source at the theatre.

The incident left one of the world's most renowned dance collectives in crisis amid reports of years of furious infighting among its dancers.

Filin himself said after the attack that he received threatening phone calls and had the tyre of his car slashed in the weeks preceding the attack.

Several Bolshoi members have already been questioned as witnesses as part of the case.

The former dancer has said several times that he knew who may have ordered the attack and blamed the incident on personal rivalries at the venerable theatre.

Filin has been replaced as the ballet's artistic director on an interim basis by veteran ballerina Galina Stepanenko.